Heretofore, end closure score line pre-breaker mechanisms have included components which extend into the open top, for example, the pre-breakers included in the carton forming, filling, and sealing machines disclosed in U.S. Pat. Nos. 3,239,995; 3,249,025; 3,820,303; and 4,044,656.
It is conventional in such machines for flat, sleeve-form carton blanks to be opened into rectangular sleeve form and the sleeves loaded in turn onto mandrels of a rotary, indexing turret. While on the mandrels, bottom end closures of the cartons are formed by pre- breaking, folding and heat-and-pressure sealing. Then the bottom-closed cartons are advanced by an indexing, linear conveyor through pre-breaking, filling, folding and heat-and-pressure sealing stations to form filled and sealed, gable-top cartons with a top sealing fin. The cartons may or may not be brought to a flat-top form by tacking-down the sealing fin. The top end closure comprises four substantially rectangular panels of which two provide roof panels and of which the other two are sub-divided into three triangular panels which extend inwards to provide recessed gable ends, as well as providing the sealing fin. Score lines intermediate the four end closure panels and respective body panels and score lines among the triangular panels of each group of three triangular panels are pre-broken by folding inwards the four end closure panels. The four panels are still in that somewhat inwardly-folded condition when they arrive at the filling station, so the plan area available for filling purposes is less than immediately before pre-braking. Moreover in the direction of advance of the carton through the filling station, the internal dimension of the rim of the mouth of the carton and thus the time period between the earliest point in time at which filling can commence and the latest point in time at which filling can terminate are shortened relative to such carton immediately before pre-breaking. Moreover, if the open-topped carton is to be sterilized internally by spraying with liquid sterilant and then dried by sterile hot air, it is advantageous for reasons of access to the interior of the carton by the sterilant and the hot air if the sterilization and drying are performed prior to prebreaking, but then the insertion into the carton of a center-post of a known pre-breaker runs the risk of recontamination of the carton interior. Furthermore, if the filled carton is to be heat-and pressure-sealed by applying hot air to selected zones of the thermoplastics internal surfaces (and possibly of the thermoplastics external surfaces) of the top end closure panels to render those zones tacky and then folding the panels inwards and clamping them together between sealing jaws, it is difficult to render tacky the acute-angled, internal, very corners among the panels because the acute-angled form of those corners militates against easy access by the hot air.